Low Information
S.01 on Vaillant ecoTEC Pro / ecoTEC Plus

Your boiler is currently preparing to start the heating cycle and is warming up the internal fan.

Reviewed by the BoilerFaultCodes Editorial Team · Last reviewed

Monitor it

This is a minor fault. Keep an eye on it and mention it at your next annual boiler service. Reset the boiler and see if it clears.

Technical description

Heating mode fan start-up

What causes this fault?

This code appears when the boiler’s internal computer tells the fan to begin spinning in preparation for a heating cycle. It is a normal part of the ignition process where the fan clears the combustion chamber and ensures a safe flow of air before the gas is lit. If the code stays on screen for a long time, it may suggest the fan is struggling to reach the required speed.

DIY fix possible

This fault may be fixable without an engineer. Check your manual first.

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Related fault codes

S.02View →S.03View →S.04View →

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